This invention will be discussed in relation to support devices used as insulators to support electrically conducting lengths of material, particularly in relation to security fences. However, it should be appreciated that the principles of the present invention can be applied to the support of many other non-electrically conducting lengths of material in various different situations.
Insulators have been in use for many years for supporting and insulating the wires or other conductors used in electric fences.
Existing insulators commonly have a backing surface and two support fingers for supporting the wire at attached to the backing surface. The fingers will now be referred to as upper and lower support fingers.
These fingers are positioned so that the free end of the upper support finger is directed towards the fixed end (on the backing surface) of the lower support finger. Similarly, the lower support finger is positioned so that its free end is directed towards the fixed end (on the backing surface) of the upper support finger.
The free ends of both support fingers are positioned side by side so that they may overlap. This overlap of the free ends effectively creates a gap between the two support fingers through which a wire may be passed and subsequently restrained by the fingers.
In practice it is only what may be referred to as the lower support finger which actually supports the wire. The function of the upper support finger is to prevent any movement of the wire, (for example by wind) which could lead to the wire being no longer able to be supported by the lower support finger.
As the upper and lower fingers are functionally identical there are two equivalent orientations for supporting the wire should the insulator be rotated through 180 degrees to an alternate orientation. This feature allows for easy mounting of this type of insulator to fence posts or other vertical supports. This is because the person responsible for mounting these devices need not concern themselves with which of two possible orientations the insulator is to have, as functionally the two orientations are equivalent.
However there is a problem associated with current insulators when they are used in electric security fences.
This problem arises as the current insulators have functionally equivalent support fingers which, in addition to supporting the wire are capable of supporting the extra weight of a person. Hence people are able to climb the security fence wires commonly near the pole to which the support devices are attached. Thus, allowing the intruder to breach the perimeter enclosed by the security fence without detection.
Sometimes the insulator itself and its attachment to the pole gives sufficient support to an intruder who climbs directly on the insulator to scale the security fence.
While this situation may be solved by manufacturing a less rugged insulator, there are situations when it is desirable to be able to scale security fences when they are not operable (ie: say in a school). A less rugged insulator could not be used in this situation.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.